Part 1 and 2: Viruses

What is DNA again?

DNA is a molecule in your cells’ nuclei that can be used as instructions by your cells to make new cells, and pigments for your hair and skin.

What is DNA again?

The DNA instructions are really a pattern of 4 different chemicals read as a code by the cell’s nucleus.

Everyone’s DNA has a different code, Except for Identical Twins.

What is DNA again?

All living things have DNA, even bacteria cells!

But if the DNA is corrupted, then problems can happen…

What are viruses?

--a non-living piece of DNA protected by a protein coat. It cannot reproduce on its own, or move without help.

What are viruses?

--Viruses have many different shapes.

What are viruses?

Viruses have no organs at all, and need to invade and take over cells so it can reproduce.

The Lytic Cycle

The Lytic Cycle is the name of the process where a virus infects a cell, and make it reproduce more viruses.

1. Lytic Cycle

1. A virus attaches itself to the cell, and injects its DNA into the cell.

2. The viral DNA gets inside the cell’s nucleus.

Lytic Cycle

3. The virus DNA takes over the nucleus, and makes the cell’s ribosomes build new virus parts without stopping.

1. Lytic Cycle

4. The cell then assembles the viral parts into new viruses.

1. Lytic Cycle

5. Eventually, the cell gets filled with so many viruses, it explodes and dies.

1. Lytic Cycle

6. The viruses will escape the dying cell, and infect new cells, restarting the cycle.

Disease Example: Common Cold

1. Lytic Cycle

Some viral DNA can quietly stay in your cells for years and years after infection.

The infected cells make new infectedcells with the same viral DNA inside them over the years.

Lytic Cycle

Suddenly, under stress, age, or other conditions, the viral DNA can suddenly activate.

When the viral DNA activates, thousands of cells will begin making viruses all at the same time, causing illness.

Lytic Cycle

Example: Shingles, caused by the same virus that causes

the Chicken Pox.

Fighting virus infections

--Antibiotics are chemicals that are designed to kill single-celled organisms, like bacteria and protists.

(anti = against ; biotic = living things)

Fighting virus infections

--Antibiotics are useless against viruses since viruses are not living organisms.

You can’t kill what’s not alive!

Fighting virus infections

To recover from a viral infection, your body can only fight off the viruses.

Cold “medicines” do not fight the viruses, they relieve your body of pain and pressure caused by the viruses.

Fighting virus infections: Vaccines

--Vaccines prevent viral illnesses by using deactivated or, harmless virus to “train” the immune system to fight viruses, like a practice battle.

vaccines

1. The vaccine adds the harmless version of a virus into your body.

Your white blood cells attack and destroy the harmless viruses.

Vaccines (ANTIBODIES)

2. The body’s Immune System then creates antibodies for that type of virus.

Vaccines (ANTIBODIES)

An antibody is a special protein that identifies and alerts the white blood cells of “invaders” in the blood.

Fighting virus infections

In the future, if the virus infects the body, antibodies alert the white blood cells to the virus, and attach to the virus.

Fighting virus infections

The antibodies slow down and hold the virus so the white blood cells can eat them.

Fighting Virus infections

--many people still continue to get viral infections like the cold and flu over and over again, even with vaccines.

Fighting Virus infections

--This happens because certain viruses can change their bodies so that the blood’s antibodies and white blood cells don’t recognize them.

Fighting Virus infections

If the body does not recognize them, as a threat, then they will not attack them.

Fighting Virus infections

But, if you recover from 1 type of the cold/flu, your body will develop antibodies against it, and you will never get that type of viral infection again.